System and method to measure tissue biomechanical properties without external excitation

Abstract

A system and method for measuring biomechanical properties of tissues without external excitation are capable of measuring and quantifying these parameters of tissues in situ and in vivo. The system and method preferably utilize a phase-sensitive optical coherence tomography (OCT) system for measuring the displacement caused by the intrinsic heartbeat. The method allows noninvasive and nondestructive quantification of tissue mechanical properties. Preferably, the method is used to detect tissue stiffness and to evaluate its stiffness due to intrinsic pulsatile motion from the heartbeat. This noninvasive method can evaluate the biomechanical properties of the tissues in vivo for detecting the onset and progression of degenerative or other diseases and evaluating the efficacy of therapies.

What is claimed is: 
     
       1. A system for quantifying biomechanical properties of tissues in a subject, comprising:
 a phase sensitive low coherence interferometry or optical coherence tomography subsystem for imaging the tissues and measuring intrinsic displacements in the tissues resulting from a heartbeat of the subject; and 
 a data processor programmed with an algorithm for quantifying biomechanical properties of the tissues based on the intrinsic displacements. 
 
     
     
       2. The system of  claim 1  wherein the algorithm quantifies one or more of phase difference, displacement amplitude, strain, elasticity, bulk modulus, and Young's modulus of the tissues. 
     
     
       3. The system of  claim 2 , wherein the algorithm quantifies displacement amplitude, wherein the displacement amplitude is calculated using phase-sensitive measurements, speckle tracking, motion tracking, or digital correlation methods, and wherein the displacement amplitude is in any direction. 
     
     
       4. The system of  claim 1 , wherein the data processor corrects the intrinsic displacements to remove motion caused by forces other than the heartbeat before quantifying the biomechanical properties of the tissues. 
     
     
       5. The system of  claim 1 , wherein the tissues are ocular tissues. 
     
     
       6. The system of  claim 1 , wherein the phase sensitive low coherence interferometry or optical coherence tomography subsystem images the tissues in  2 D,  3 D, or  4 D. 
     
     
       7. The system of  claim 1 , wherein the optical coherence tomography subsystem images the tissues.